PROJECT SUMMARY/ABSTRACT Cardiovascular disease (CVD) due to atherosclerosis represents the leading cause of death worldwide. Progress in preventing CVD has been stalled by the growing epidemic of obesity, insulin resistance and type 2 diabetes (T2D), which increases the relative risk of developing atherosclerotic vascular disease and its complications four-fold compared to non-diabetic individuals. Despite this, the cellular and molecular mechanisms underlying the incidence of diabetic atherosclerosis are still unclear, as are appropriate strategies for the prevention and treatment of CVD in diabetic patients. We have recently developed an orally available, liver-directed controlled release mitochondrial protonophore (CRMP) that promotes oxidation of hepatic triglycerides by promoting a subtle sustained increase in hepatic mitochondrial inefficiency and shown that this agent safely reverses hypertriglyceridemia, fatty liver, insulin resistance and liver fibrosis in rodent and nonhuman primate models of obesity. Here, we will leverage the insulin-sensitizing effects of CRMP to directly assess the role of hyperinsulinemia and insulin resistance in driving diabetic atherosclerosis in a murine model of metabolic syndrome (Aims 1 and 2). We hypothesize that chronic CRMP treatment will reduce hepatic steatosis, insulin resistance and dyslipidemia due to increases in rates of hepatic mitochondrial fat oxidation, which in turn will reduce susceptibility to atherosclerosis. In addition, we will develop and utilize novel state-of- the-art metabolic tracer methods to characterize the regulation of macrophage immunometabolism during diabetic atherosclerosis (Aim 3), as the relationship between the inflammatory status and bioenergetic profile of plaque macrophages in vivo, as well as its impact on atherosclerotic development and stability, remains largely unknown. We hypothesize that obesity and T2D will increase glucose availability and utilization in macrophages which will initiate a feed forward loop that fosters inflammation and further aggravates atherosclerosis Collectively, this work will provide meaningful insight into the mechanisms regulating diabetic atherosclerosis and will be critical for understanding the therapeutic utility of liver-directed mitochondrial uncoupling agents for the treatment of cardiometabolic diseases. Therefore, we propose a focused career development training plan during which the applicant will be trained in the responsible conduct of research, learning all aspects of atherosclerotic plaque sectioning and characterization; the development and utilization of stable isotope methods to assess macrophage immunometabolism; and bioinformatics analysis of large data sets. This will be carried out under the supervision of the candidate?s primary mentor Dr. Gerald Shulman, co- mentor Dr. William Sessa, and collaborators Drs. Carlos Fernandez-Hernando and Rachel Perry. By completing the proposed training outlined in this application (K99), the applicant will obtain the knowledge and skills that will provide her with the initial steps towards scientific autonomy in the subsequent phase (R00) and transition successfully from the role of postdoctoral trainee to that of an independent researcher.